1. Technical Field
The present invention relates to a projector.
2. Related Art
To date, as a front projection type projector, a configuration has been known which employs a short focus projection optical device in which a projection distance is shortened in order to improve the degree of freedom in installation of the projector (refer to JP-A-2007-334052).
2. Related Art
In a projector described in JP-A-2007-334052, a projection optical device includes, at the last stage of the optical path therein, an aspheric mirror having a reflecting surface which, being formed as a free-form surface, is not of rotational symmetry. Then, by an image light being reflected by the aspheric mirror, the angle of the image light is widened via a luminous flux passage opening provided in a first surface of an exterior casing. By means of this kind of configuration, it is possible to install the projector in a position close to a wall surface on which a screen is installed, improving the degree of freedom in installation of the projector.
However, with the projector described in JP-A-2007-334052, as the aspheric mirror is in a condition in which it is exposed via the luminous flux passage opening, there is a problem in that it is difficult to efficiently maintain a projection image in a clear condition, due to dust adhesion to the aspheric mirror, contamination of the aspheric mirror caused by handling it, or an impact on the aspheric mirror caused by handling it or the like.